1. Field of the Invention
This invention relates to a device for the detection of at least one ligand contained in a sample that is to be analyzed, with an optical waveguide, on the surface of which at least one receptor is directly or indirectly immobilized which, when it comes into contact with the ligand, forms a specific bond with the ligand, with at least one optical source of radiation for injecting excitation radiation into the waveguide, the radiation being used to excite the emission of luminescence radiation in accordance with the bonding of the ligand to the receptor, and with a semiconductor chip that has at least one radiation receiver on a semiconductor substrate to detect the luminescence radiation.
2. Description of the Prior Art
A similar device of the prior art is described in DE 100 02 566 A1. On the surface of a planar optical waveguide it has a plurality of measurement points at which specific nucleic acids are immobilized in the form of receptors. A liquid sample to be analyzed and that contains nucleic acids that are complementary to the receptors is placed in contact with the receptors. These nucleic acids bind to the specific receptors to which they are complementary. The receptor-ligand complexes that have nucleic acids that are complementary to each other are marked with a luminescent substance. By means of a laser diode, for example, an excitation radiation is generated and injected into the optical waveguide. An electromagnetic field, also called the evanescence field, is generated in a layer of the sample that is adjacent to the boundary surface by total reflection on the boundary surface of the waveguide. This field penetrates into the liquid sample to a depth of only a few hundred nanometers from the boundary surface. To emit luminescence radiation, the evanescence field excites almost exclusively the luminescent substance that is bonded to the surface of the waveguide. For the detection of the nucleic acids that are contained in the sample, the luminescence radiation is detected by means of a CCD camera with a high degree of local resolution. The CCD camera is located on the reverse side of the waveguide facing away from the receptors. It has an optical imaging system that images each of the individual measurement points located on the surface of the waveguide on the respective detector elements of a CCD sensor. The disadvantage of this device is that it still has a relatively large number of system components and is therefore correspondingly complex and expensive. An additional disadvantage is that the device is relatively large. Finally, the measurement sensitivity of the device leaves something to be desired.
The object of the invention is therefore to create a device of the type described above which makes it possible to have a compact size with a simple and economical construction.